The instant invention relates to link forming apparatus having particular application in the jewelry industry wherein the links as formed are joined to preformed jewelry articles, such as chains and findings.
Link forming and joining devices have heretofore been known in the art. In this regard, the U.S. Patent to Crafford et al, U.S. Pat. No. 3,841,088 represents the closest prior art to the subject invention of which the applicant is aware. The Crafford patent discloses a link forming and joining device wherein the device is operable by a set of cams for automatically feeding wire stock to a cutting and forming station at which the wire stock is severed into a plurality of wire sections, the wire sections being bent into a "U" configuration, and stored in a magazine, and then being individually transferred from the magazine to a forming station for joining to a preformed jewelry article, such as a chain for finding. More specifically, the wire sections are severed and bent into a U-shaped configuration at one station and then transferred into a magazine which is operative for storing as many as 100 to 150 U-shaped wire elements for use. The front end of the magazine communicates directly with a guide assembly having a vertical guide passage. The guide assembly locates the wire elements in oriented position for vertical movement through the guide passage to a forming station located at the top of the guide assembly. A lower forming tool is located in the passage of the guide assembly and is operated in timed relation by a cam to lift an individual U-shaped wire element to the forming station. Another cam is operable for simultaneously drawing a forming head die downwardly toward the guide assembly, the forming head die cooperating with the lower forming tool to form, the U-shaped wire element into a completed link, or ring, thereby joining the link to a preformed jewelry article, such as a chain or finding.
While the link forming and joining apparatus as described above has satisfactorily served its intended purpose, its operation has several drawbacks related to a need to be able to quickly and easily change from using one size wire stock to another size wire stock. Small jewelry manufactures often produce jewelry articles in batches of as few as fifty pieces, each different type of article usually requiring a different size wire stock for joining to a chain, etc. Since each size wire stock requires a corresponding set of cutting, bending and forming dies, each time a manufacturer switches to production of a new article, and a new size wire stock, the cutting, bending and forming dies must be removed and replaced with the desired sizes. Manufacturers have found it very difficult to quickly change such dies in the prior art apparatus.
Another drawback related to changing wire stock sizes has been difficulty in adjusting the length of wire section being fed into the cutting station after a new size wire stock is installed. The length of the wire section severed from the wire stock is critically important in assuring that the link is properly formed and joined, too little wire resulting in a partially open link, too much wire resulting in a deformed shape due to excess material in the die.
Yet another drawback has been the use of a magazine for storage of a plurality of preformed U-shaped wire elements prior to use. The wire stock used to form the links is primarily precious metal wire stock, such as gold or silver wire. Since manufactures often run small batches of as few as fifty jewelry articles, each time a manufacturer switches to a different size or type of precious metal stock, there are approximately 100 to 150 unused U-shaped wire elements still left in the magazine. Since the wire elements are precious metal and cannot be reinserted into the magazine after removal, the manufacturer usually saves and recycles the unused pieces. However, the waste and extra expense from this arrangement is problematic for some manufacturers.
The instant invention provides a link forming and joining apparatus which overcomes the drawbacks of the prior art device. The instant link forming and joining apparatus comprises a guide assembly including a vertically extending guide passage therein, the passage having a lower end for receiving a U-shaped wire element therein with an open end of said U-shaped wire element facing upwardly. The passage further has an upper end defining a forming station, the passage defining a vertical working plane. The apparatus further comprises a lower forming tool mounted for sliding movement in the passage for engaging a U-shaped wire element in the passage and lifting the U-shaped wire element from the lower end of the passage to the forming station at the upper end. A forming head assembly is located above the guide assembly, wherein the head assembly includes a forming head die mounted for vertical movement within the working plane for engaging a U-shaped wire element situated at the forming station during a forming operation. More specifically, the forming head die cooperates with the lower forming tool to close the open end of the U-shaped wire element during the forming operation. In use, a link of a chain and a link of a jewelry finding are placed over the upwardly extending arms of the U-shaped wire element prior to forming. When the forming operation is performed, the link is closed to join the chain to the finding. The apparatus still further comprises means for feeding wire stock to a cutting and bending station located within the working plane at the lower end of the passage, means at the cutting and bending station for severing a wire section from the wire stock, and means at the cutting and bending station for bending the wire section into a U-shaped wire element within the working plane. The feed mechanism, the severing device, the forming device, the lower forming tool and the forming head die are all operated in timed relation by a cam system for sequentially severing, bending and forming the U-shaped wire element in a single link forming operation.
The means for severing the wire section from the wire stock comprises a guide block having a terminal edge disposed adjacent to the cutting and bending station, and a vertically movable carriage having a pair spaced forming arms, one of the forming arms being disposed in closely spaced sliding relation with the terminal edge of the block. In operation, the forming arm engages the wire section extending from the guide block and severs the wire section from the wire stock when the carriage is moved upwardly.
The means for forming the wire section into a U-shaped wire element comprises a retractable arbor extending through the working plane at the cutting and bending station and further extending between the forming arms of the carriage. The terminal upper edges of the forming arms include a groove for holding a respective end of the severed wire section. The forming carriage is operative for lifting the severed wire section upwardly into engagement with the arbor wherein the forming arms bend the respective ends of said wire section upwardly around the arbor to form a U-shaped wire element.
The means for feeding the wire stock to the cutting and bending station comprises a feed block assembly and a feed clamp assembly mounted on the feed block assembly. The feed block assembly comprises a body portion, and a horizontally extending guide bar mounted to the body portion, with the feed clamp assembly being slidably mounted on the guide bar for movement between first and second positions. The feed clamp assembly receives a length of wire stock therethrough and includes means for selectively clamping the wire stock. The feed block assembly further comprises a pivotably mounted lever having a first end pivotably mounted to the feed clamp assembly and a second end coupled to an actuator arm of the link forming apparatus, the actuator arm being movable for actuating the feed clamp assembly between the first and second positions. The lever includes a plurality of apertures therein for receiving a pivot pin attached to a pivot block slidably mounted in the body portion. The pivot pin defines a pivot axis of the lever and is selectively extended through one of the lever apertures to adjust the vertical position of the pivot axis. The pivot block is then slidably adjustable within the body portion by means of a threaded rod extending vertically through the pivot block for finite adjustment of the vertical position of the pivot axis. In operation, the adjustment of the vertical position of the pivot axis adjusts the horizontal travel of the feed clamp assembly thereby adjusting the length of the wire section fed into the cutting station.
Accordingly, among the objects of the instant invention are: the provision of a link forming and joining apparatus in which the die sets are easily removed and installed with minimum time and effort; the provision of a link forming apparatus including a simple adjustment mechanism for adjusting the travel length of the feeding mechanism; and the provision of a link forming and joining apparatus which performs a single wire section into a U-shaped configuration and individually transfers the wire element to a closure station without the use of a magazine.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.